The present disclosure is directed to an indexable double-sided tangential cutting insert and a cutting tool system, which use such double-sided tangential cutting inserts, for a variety of rotary milling applications. In one non-limiting specific embodiment, indexable double-sided tangential cutting inserts according to the present invention are particularly useful in peripheral rotary milling applications for machining difficult-to-machine materials. In another non-limiting specific embodiment, indexable double-sided tangential cutting inserts according to the present invention are uniquely useful in peripheral rotary milling applications that generate segmented chips, for instance, when machining cast-iron and alloys or medium to high carbon steels.
A double-sided tangential milling cutting insert is generally defined as the cutting rake faces where the chip groove/chip breaker does not have a through fastener hole, or in other words, the through fastener hole is located between two cutting rake faces, but in a laterally-crossed orientation. For a double-sided tangential cutting insert, all cutting rake faces with built-in chip groove geometry must have an abutment face to support the tangential cutting force during the machining.
Efforts in the industry to develop new or improved double-sided tangential cutting inserts have been directed toward achieving reduced cutting forces, reduced power consumption, increased cutting edge strength, and increased tool life. Representative patent documents include U.S. Pat. No. 6,872,034, U.S. Pat. No. 7,063,489, U.S. Pat. No. 7,094,007, and U.S. Pat. No. 7,104,735 wherein these documents have disclosed double-sided tangential cutting inserts with two basic shapes in major side surfaces (trapezoidal and parallelogram) and varying abutment surfaces on the cutting rake surface. From the point view of geometrical design, the above-mentioned patents disclose a generally rectangular shape peripherally enclosed by the two planar major side faces, two planar minor side faces and together with four nose faces as viewed normally to the cutting rake surface of the double-sided tangential cutting insert, or in other words, the main cutting edge is perpendicular to the minor cutting edge. The drawbacks with the kinds of cutting inserts disclosed in these patents include a difficulty to effectively balance on the required surface finish and the perpendicularity between the machined surface and machined wall on the workpiece which occurs, for example, in a slot milling, largely due to the complex cutting edge geometry in particular on the minor cutting edges formed between the cutting rake face and the minor side face.
The present invention aims at developing an improved double-sided tangential cutting insert, as well as a cutting tool system using the improved double-sided tangential cutting insert, to address the above-mentioned issues.